This application is submitted for the partial funding of the first conference on Protein Phosphatases to be held under the auspices of the Federation of American Societies of Experimental Biology (FASEB) August 5- 10, 1990 in Copper Mountain, Colorado. As usual, participation will be limited to 150 scientists (including speakers and moderators), selected on the basis of their expertise and interest in this area and their expected contribution to the success of this program. It will be the first meeting entirely devoted to Protein Phosphatases: their structure, function, regulation at the protein and genetic level and role in the control of cellular processes as they occur in health and disease. The Conference will consist of nine sessions, each with four speakers and a discussion leader; selected among investigators who have made seminal contributions to this field. In addition, poster sessions will be held that will provide an opportunity for more junior participants to present their data and discuss them with authorities in the field. This meeting will bring to light the sum of evidence now indicating the crucial role Protein Phosphatases are playing in such physiological processes cell cycle, growth, differentiation and transformation.